Categorical data does not contain the quantitative(numeric) values it has only the names, colors, etc.
We cannot measure this type of data and even it cannot be ordered.
Mode is the most frequent value in the categorical data.
For example-
There is no quantitative value in this table, so we cannot find out the mean and median of the data.
We can find out the most frequent value, which is the RED color.
Hence, we can use mode as a measure of central tendency in categorical data.